Взаимосвязь конденсации влаги и образования пирофорных соединений в парогазовом пространстве резервуаров с сернистой нефтью

Abstract

Purpose. When storing sulfurous oil in vertical steel tanks, pyrophoric corrosive deposits are formed on their inner surface after a while, and they are capable to self-ignite under certain conditions. It is assumed that the rate of corrosion and that of forming pyrophoric deposits will depend on the humidity of the steam-gas medium inside the vertical steel tank and the conditions of its water fraction condensation on the oil tank inner surface. The main purpose of the research is to determine humidity impact on the inner surface of the roof and upper belts of tanks with sulfurous oil on the rate of corrosion and growth of pyrophoric compounds. Methods. To study the relationship between the humidity of the inner surface of the tanks with sulfurous oil, the temperature regime inside and outside the vertical steel tank and the growth rate of pyrophoric deposits, the method of experimental data analysis was used. Experimental results were obtained using an experimental method consisting of full-scale testing of low-carbon steel samples in tanks with sulfurous oil. Findings. The dependence of the amount of moisture and that of pyrophoric corrosive deposits formed on the inner surface of the tank with sulfurous oil on the type of the stored product and the season of year is revealed. A direct correlation is obtained between the amount of pyrophores formed and the amount of condensed moisture. Research application field. The results can be used in planning activities to ensure fire safety at the facilities of the oil and gas industry, as well as to ensure fire protection of vertical steel oil tanks. Conclusions. The results of the study allowed the authors to draw a number of the following conclusions: 1) when the inner surface of oil tanks comes into contact with the steam-gas medium, moisture condensation and the formation of pyrophoric deposits occur on the metal surface; 2) there is a correlation between the rate of pyrophoric deposits formation and the humidity of the tanks’ inner surface that are in contact with the steam-gas medium – the higher the humidity the greater the rate of pyrophoric deposits formation; 3) the growth rate of pyrophoric deposits is determined by the conditions of heat transfer on the tanks surface and is minimal at similar temperatures inside and outside the tanks, which are typical for the summer months and sunny spring-winter days; 4) high humidity of the tanks’ roof inner surface suggests the possibility of using tread protection to reduce the rate of pyrophoric deposits formation.